The present invention relates to a staple clinching mechanism for bending the legs of a staple driven by the driver of a stapler in a clincher portion after the legs thereof are passed through sheets of paper.
Staplers are used for binding sheets of paper by bending the legs of U-shaped staples substantially to right angles after the staples are driven into and passed through the sheets of paper. Since the legs of such a staple are normally bent so that the pointed ends of the legs are directed closer to each other, the legs may collide and interfere with each other, thus resulting in bending inappropriately.
In order to obviate the aforesaid inconvenience, a heretofore known method is, as shown in FIG. 11, to place the boundary 21 between bend guiding surfaces 20a, 20b on either side of a clincher portion 20 in a position deviating toward one leg-bending surface 20a. With the clincher portion like this, the legs 22 of a staple are brought into contact with the respective bend guiding surfaces 20a, 20b of the clincher portion after the legs are passed through sheets of paper and the leading ends of the legs are increasingly curled while they are being guided inward. Since the boundary of the clincher portion is deviated to one side, the deviation causes the leading end of the leg 22 on the left-hand side in FIG. 11 to be rapidly curled, whereas the leg 22 on the right-hand side is curled after some delay. Consequently, the leading end of the leg 22 that has been bent after some delay is so formed as to hold tightly to itself what has been bent previously, whereby the legs are prevented from interfering from each other.
However, even the aforesaid clinch mechanism has not succeeded in thoroughly preventing the leading ends of the legs from interfering with each other, thus allowing the legs to be bent inappropriately.